I would say this is THE MOST DIFFICULT curriculum to choose. For me at least.
There is just not a lot out there outside of the Biblically based.
I looked into doing what The Well-Trained Mind by Jessie and Susan Wise recommended for first-graders but it seemed way too easy and basic. So I bought Building Foundations of Scientific Understanding (BFSU) and hated it (see review HERE).
My old school just uses the Core Knowledge Sequence and supplements. I’ve been using a combination of all three.
Why is there a lack of a good science curriculum? I ask myself.
Still don’t know.
I think Science is hard to teach to little kids because of all the difficult content involved, advanced work in mathematics it requires, and higher order thinking skills. But it needs to be done and can be done. I just haven’t discovered anything yet that meets my needs.
So next year I will be on the search again so any recommendations would be much appreciated.